*{
    margin: 0;
    padding: 0;
}

body{
    background-color: #000;
    color: #666;
    text-align: center;
}

audio{
    width: 450px;
    margin: 30px 0;
}

.container{
    height: 420px;
    overflow: hidden;
    /* border:2px solid #fff */
}

.container ul{
    /* border: 2px solid red; */
    transition: .6s;
    list-style: none;
}

.container li{
    height: 30px;
    line-height: 30px;
    transition: .2s;
}

.container li.active{
    color: #fff;
    transform: scale(1.2);
    /* 这里字体放大不用font-size 因为会造成位移*/    
}